Generally, when conducting work for loading excavated objects into a dump truck using a hydraulic excavator that is a construction machine, then an operator causes a work implement to execute a boom raising action while controlling an upper swing structure to rotate or swing by operator's simultaneous adjustment of a swing angle and a height of the work implement using operation devices, and moves the work implement from an excavation position to an upper position of a cargo stand of the dump truck to discharge the excavated objects.
The upper swing structure continues swinging through inertia even after the operator stops a swing operation, and a swing stop angle varies depending on a swing speed and swing inertia at the time of stopping the swing operation. For this reason, it is necessary to determine stop timing of the swing operation in the light of an increase of the swing stop angle by the inertia for stopping the upper swing structure at a desired swing angle. In this way, when performing a combined operation involving the swing action or the swing stop operation for stopping the upper swing structure at a desired position, the operator is required to operate the hydraulic excavator with a higher degree of concentration. In addition, operator's monitoring awareness of surroundings is diminished because of the concentration of awareness on operating the hydraulic excavator. For example, when an approaching object to a swing range of the work implement is present, the discovery of the approaching object is possibly delayed.
There are known a construction machine swing control system and a method thereof that can stop an upper swing structure in a predetermined range even if an operator stops a swing operation for which the operator is required to have a high degree of concentration as described above at different timing (refer to, for example, Patent Document 1). According to the construction machine swing control system and the method thereof, an optimum swing-operation-stop starting position for stopping the upper swing structure in the predetermined range is estimated, a stop target position is calculated using a current swing position and the stop starting position, and a swing motor is then controlled such that the upper swing structure is stopped at the stop target position. It is thereby possible to stop the swing of the upper swing structure in the predetermined range even if the operator stops the swing operation at the different timing.
There are also known a swing work machine and a swing work machine control method for detecting an approaching object described above to a swing range of the work implement and stopping the swing (refer to, for example, Patent Document 2). According to the swing work machine and the swing work machine control method, it is determined whether there is a probability of interference between the swing work machine and the approaching object on the basis of a current swing speed, current swing inertia, and a position of the approaching object, and a swing action is controlled.